<!DOCTYPE html> 
<html lang="en"> 
<head> 
<meta charset="UTF-8"> 
<meta name="viewport" content="width=device-width, initial-scale=1.0"> 
<title></title> 
<script> 
   const obj = {}; 
   // 为 obj 对象添加一个属性，是可以的 
   obj.age = 23; 
   console.log(obj.age); // 23 
   // 尝试修改 obj 的引用地址，就会报错 
   // Uncaught TypeError: Assignment to constant variable. 
   obj = {}; 
   </script> 
 </head> 
 <body></body> 
 </html> 